Condition indicator for electric fuses



Dec. 23, 1952 w. 'r. WALLACE ETAL CONDITION INDICATOR FOR ELECTRIC FUSES Filed May 51, 1949 In ventors Wilmer 7: Wallace James E. Coon/ey 4062M paw fiM By mu Patented Dec. 23, 1952 UNITED- STATES PATENT omcs Wiimer' T: Wallace and J ames E; Coonley, Hampton, Iowa This invention relates to c'onditio n indicators for electric fuses and it has for itsmain object to provide a simple and effective indicator means adapted for permanent association with or a permanent incorporation into the fuse block or fuse box which indicator is capable to point out those fuses which have burned out among a relatively large number by a simple means-operated by a very simple manipulation.

It is moreover an object of the invention to provide a fuse indicator for fuse boxes or blocks containing or numbering relatively large number of main supply and branch lines, each provided with a fuse, in which the number of indicating lamps or bulbs and the number of switches necessary for examining the condition of all the fuses of the box or blocks is reduced to a minimum, the indicator being normally out of operation, but when operated indicating rapidly the condition of all the fuses of the'box or block in succession.

It is a further object of the invention to provide a fuse condition indicator for fuse boxes or blocks which may be permanently associated with the said fuse box or block and which is-normally inoperative but which, when made operative by means of a simple manipulation, rapidly provides a complete indication valid for all the fuses of a box or block, the testing means of the fuse condition indicator beingaccessible from without so that no opening of the closed box is required for the testing operation. 7

It is a further object ofthe invention to associate a fuse condition indicating and fuse testing arrangement, as described in the preceding paragraph, with the door or closure plate of the fuse box in a manner permitting manipulation from the outside while arranging thedevice its elf 'substantially within the box, and connectingth'e device with the fuses in such a manner that easy disconnection takes placeupon opening of the door of the fuse box for the replacement of fuses or for other repair or replacement work.

Further objects of the invention are "more specific and will be apparent from the detailed spe cification.

The invention'is illustrated in the accompanying drawings byway of example, one modification of the invention being shown. However, it is to be understood that this modification shown by way'of example has been selected in order to explain the principle of the invention andthe best mode of applying this principle. Modificationsof the example shown, therefore, do not necessarily constitute a departure fromtheprincipleof the invention.

Applicationltiay' 31, 1949, Serial Nb. an;

In the drawings; V

Figure 1 is a diagram showing one of the customary fuse boxes orfuse block's, its connection with a main supply'a'rid branch lines and its'connection with a'ruseeonumcn indicator.

Figure 2 is an elevational view of the (1601' of a fusebox equipped with the indicating device.

Figure 3is a plan View partly'in section of the fuse box with the'door' open.

Figure 4 is a sectional view along the vertical plane of symmetry through the indicator and through thew'all to which the indicator is attached.

Figure 5 is a vie'w of a back plate of a fuse box which is provided with a'seco'ndar'y' door with the indicator mechanism inplace'on said back plate. V I

As above explained the invention consists essentially in a simple'indicator for the condition of the fuses of a fuse box'o'r fuse block which may be associated permanently with the said box or block but which is not permanently operated but only becomes operative when manipulated and when a testing operation isstarted, which tests rapidly all'the fuses or'the'fuse box in succession revealing immediately those which are defective or burned out.

A fuse box provided'with a condition indicator according to this invention is generally indicated by the reference numeral 5. It contains the fuse block indicated at 6 in Figure '1 which need not be described as it merely shows one ofth'e numerous well xnownar'rangemems in which main or through lines indicatedat'a and branch lines indicated at b are provided'with fuses i. The fuses not only have to be supervised but also have 'to be tested occasionally in order to locate the reason for a failure of 'current'in some branch circuit or the location of a fuse which is burned out after a short circuit. I

The testing indicator according to the invention consists'merely in a switch" generally indicated at8 which comprises arotajting switch arm 9 cooperating with a numberof "fixed contacts arranged in a circle, the center of Which-is coincident with the axis of the rotating'arm s. One of the positions of the switch isa neutral position in which theswitch 'arnr'doesnot make contact with any fixed contact. The switch'sis mounted within a box 39 of insulating-material which encloses the switch completely. The-rotating arm 9 is carried-by a shaft 2% with a projectingend lf! projecting through the box to the outside.

The contacts l are'forrr'ied 'by the heads of rivets or bolts'dl which project outwardly'on the 3 rear side of the box and are provided with threaded ends on which nuts 42 are held. The bolts and nuts form terminal posts for the connecting wires.

The shaft 29 is provided with a stepped portion at the point where it joins the projection se and it is held, either by the elasticity of the arm 9 or by a separate spring means 45 against a contact plate 44 which may be provided with a sleeve through which the projecting portion 40 of the shaft passes to the outside.

Moreover, the box 39 is provided with a lamp socket 45 holding a small indicator lamp bulb 58, projecting from the box outwardly. The lamp socket may be provided with an extension 41 projecting inwardly into the box and forming a contact prong for a connection wire 5|.

The central contact of the lamp bulb is formed by a small contact spring 48 projecting from and held on the side wall of the box. This contact spring is also connected with a further wire 49 leading to the outside. The wire 5| leading to the contact prong 41 of the socket is connected on the other side with the contact plate 44 and with the shaft 29 and switch arm 9.

The projecting portion 40 of the shaft 29 preferably carries the knurled sleeve or knob 52 of insulating material which may be seized by an operator and may be turned in order to turn the switch arm 9. A pointer 54 projects from said knob r sleeve 52 and rotates with it and with the shaft 22. Therefore the pointer clearly indicates the position of the rotating arm 9.

The fuse box containing the fuse block is either provided with a door 18 as shown in Figures 2 and 3 covering the entire front of the box or the fuses are arranged behind the back plate 28 as shown in Figure 5 which is fixed within the box and which contains a secondary door 38 by means of which access may be had to the fuse block. The location of the fuse condition indicat ing device is chosen accordingly.

In the case illustrated in Figures 2 and 3 the switch box 39 is fixed on the inner side of the door i8 by means of brackets 59, and the sleeve or knob 52 carrying the pointer 54 projects through the door to the outside. The indicator lamp bulb 55 which is arranged on the outside of the box 39 is therefore arranged behind the door in the space between the front wall of the switch box and the inside of the door. The door in this case is provided with a number of holes 55 corresponding to the number of fixed contacts i5 and also to the number of fuses connected with the said fixed contacts which form marks for the pointer or which are arranged in such relation to marks provided on the door that they can easily be identified.

In the event that a box with a back plate 28 and a secondary door 38 is used the indicating device is preferably mounted on the back or closure plate 28 in the manner shown in Figure 4, the switch box being mounted by means of brackets 59 at some distance from the back plate 28 and the knurled knob or sleeve 52 carrying the pointer 5d projecting from the back plate 28 towards the front side. The back plate 28 in this case is provided with holes 55 forming marks for the pointer.

Connections run from each of the fuses 1 (Figure 1) to one of the contacts l9 to the rotary switch 8. When the switch 9 is mounted on the door iii of the fuse box 5 the socket member 56 of the connector, provided with sockets 20, 2|, 22, 23, 24, 2 5, 26 and 21, may be mounted within 4 the fuse box on the wall thereof, each socket 20, 2 I, 22 21 being connected with one of the fuses 1 by means of a conductor [0, ll, [2, l3, l4,

[5, I6, I1. On the door l8 of the fuse box the plug member 58 of the connector may be arranged which cooperates with the socket member 56 and which is preferably not fixed but is loosely held by the conductors lUa, Ila, I211 I'la, which lead from the plugs 30, 3|, 32 31 to each of the fixed contacts [9 of the rotary switch 8.

'As already stated, the rotary member 9 of the switch 8 is connected by means of a Wire 5| to the indicator lamp 5!] which in its turn is connected with ground G by means of conductor 60. The ground connection of course may be identical with that of the fuse block, if such a ground connection is available on the block.

It will be clear that upon failure of current in one or more of the circuits controlled by the fuses it will be necessary to determine which fuse has blown out. In order to do this the fuses may all be tested by a simple manipulation which consists in turning the knurled knob or sleeve 52 through 369. In its original position as above mentioned, the rotary arm is not connected with any one of the contacts l9. Therefore no fuse is normally provided with the ground connection or is connected with the indicator lamp and the latter is therefore inoperative when no testing operation is under way.

When such a testing operation is undertaken and the knob or sleeve 52 is turned and the pointer 54 reaches a mark pointing towards one of the holes 55 all the holes including the one to which the pointer 54 is pointing light up, as the indicator lamp bulb lights the space between the switch box 39 and the back plate 23 or door l8. When the holes are not lighted the fuse corresponding to the hole toward which the pointer of the knob is directed is the one which is defective or which has burned out. The identification of the fuse which has burned out is therefore easily performed by any unskilled person as merely the knob has to be turned around and the operator has to stop his movement when the holes remain dark. The position of the pointer 54 in this case and the number of the hole identifies the branch circuit with a defective or burned out fuse. It will therefore be clear that the identification and replacement of the fuse even in a case in which numerous supply and branch lines are involved can be made by any person, whether skilled or unskilled.

When repair work has to be performed the electrician opens the door of the fuse box and removes the plug member 58 from the socket member 55. Then he opens the door l8 of the fuse box completely and he may now attend to the repair work within the box. Where the box has a back plate 28 with a smaller secondary door 38 as shown in Figure 5 the repair has to be undertaken through the small or secondary door 38 which is also shown in Figure 5. In this case the switch and the indicator do not affect such a repair as they may be located at a place remote from the door 38.

The invention has been described in a specific manner but it will be clear that the construction of unessential parts has no bearing on the essence of the invention and therefore changes may be made without departing from the subject matter as defined in the annexed claims.

Having described the invention, what is claimed as new is:

1. Condition indicating means for fuse boxes provided with a swingable door and servicing a number of electric main and branch lines, each provided with a thermal fuse comprising a rotary fuse condition indicator switch arranged as a separate unit at a distance from said fuse boxes, said switch, including a rotatable switch arm and a number of fixed contacts adapted to be brought successively into contact with said rotatable arm, mounted on said door, a plug and socket connection provided with a number of plugs and socket members equal to the number of lines provided with fuses and adapted for connection with each other, said socket member being mounted within the box, a connection of each fixed contact of the rotatable switch with one of the plug members, a connection of each of the socket members with one of the fuse containing lines, a common return conductor, an electric indicating lamp in said return conductor arranged behind said door, the latter being provided with holes arranged in a circle and means for manually rotating said rotatable switch arm, the lighting of the indicating lamp and the darkening of the same indicating the condition of the fuse connected with the fixed contact on which the rotatable switch arm rests.

2. Indicating means for a number of fuses contained in a fuse block or box servicing a number of electric main and branch lines, each line being provided with a thermal fuse, comprising a common fuse condition indicator unit for all fuses of a fuse block or box, arranged separately and at a distance from said fuse block or box, said unit including a rotatable switch arm and a number of fixed contacts brought successively into operative contact with the said rotatable switch arm upon rotation of the same, a. separate connection of each fuse with one of said fixed contacts of the switch, a common return conductor, an electric indicating lamp in said common return conductor, a board provided with holes arranged in a circle and angularly spaced in conformity with the fixed contacts arranged in front of the unit, a manually operated means for rotating said switch arm projecting outwardly through said board and provided with a pointer pointing to one of the holes, said indicating lamp being arranged behind said board and producing a visible illumination behind said holes, said board and switch thus indicating the condition of each fuse of the fuse block or box by the position of the rotating switch arm and pointer corresponding to the said fuse and indicating the condition of all fuses of the fuse block or box upon rotation of the switch arm.

3. Indicating means for a number of fuses contained in a fuse block or box, servicing a number of electric main and branch lines, each provided with a thermal fuse, comprising a single separately arranged indicator unit, in common to all fuses in the fuse block or box, said unit including a switch with a switch arm, rotatable around an axis, said switch arm being connected with a ground conductor, an indi cator lamp within said conductor, a number of fixed contacts arranged in a circle around the axis of rotation of the switch arm and contacted by the said arm successively during rotation, each fixed contact being connected with a terminal and each terminal being connected with one of the fuses, an insulating box housing said rotatable switch and carrying said fixed contacts and terminals on its inside and outside respectively, and further carrying said indicator lamp, the lamp bulbprojecting outwardly from said insulating box, a shaft carrying said rotatable switch, an insulating handle for manual operation of said shaft, a board provided with a number of holes equal to the number of fuses connected with the switch in front of said insulating box on the side carrying the lamp bulbs, said board being arranged between the insulating box and the handle, and an indicating pointer carried by said shaft and rotating with the switch arm, the insulating box forming a background, the illumination of which by the indicator lamp is made visible through the holes, while the pointer position indicates the hole corresponding to one of the fixed contacts of the switch, the said background illumination or darkness indicating the conducting or nonconducting state of the fuse.

WILMER T. WALLACE. JAMES E. COONLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,323,882 Lorenz Dec. 2, 1919 1,631,178 Wurdack June 7, 1927 1,645,346 Palmer Oct. 11, 1927 2,015,316 Miller Sept. 24, 1935 

